Having noticed a recent drop in mood accompanying PEM-type symptoms after a fairly-strenuous day, I have been trying to figure out why, and thought it might be of interest to others if I put my thoughts down here.
As usual, I have pulled together bits of info I have already gleaned which may relate to a chain of causation here.
The idea of physical activity causing low mood probably sounds absurd to people without knowledge of ME. After all, it is reported to improve mood in most people. However, a very quick search for scientific papers on this link did not produce any convincing-looking hits. Maybe a longer search would.
So, here goes with a very rough, simplistic theory for exertion causing depression/low mood in ME.
This paper
http://jap.physiology.org/content/82/2/571
which I have referred to in other blogposts, reports that exertion increases intestinal permeability.
It states:
“Compromised barrier function may produce an inflammatory response and initiate a cytokine cascade...”
The authors also refer to bacterial endotoxins (aka lipopolysaccharides/LPS) entering the systemic circulation from the gut via increased gut wall permeability.
This paper
http://ini.sagepub.com/content/17/3/302
states that LPS trigger production of interferons.
Interferons can induce depression/low mood, as reported in numerous papers including this one:
http://www.jad-journal.com/article/S0165-0327(07)00332-1/abstract?cc=y
Why do people with ME get this adverse effect from exercise, yet others don't?
Perhaps it is due to our abnormal/inadequate HPA axis activity, which means that we can’t produce enough cortisol to dampen down the interferon activity (the link before last discusses cortisol and interferon signalling).
And/or maybe it’s because we switch to anaerobic ATP production too quickly, leading to excessive lactate levels/acidosis?
And/or maybe we don’t produce enough endorphins to combat adverse effects?
I’m keeping this post short as I have to get on with other stuff and am quite tired, but would welcome any comments.
As usual, I have pulled together bits of info I have already gleaned which may relate to a chain of causation here.
The idea of physical activity causing low mood probably sounds absurd to people without knowledge of ME. After all, it is reported to improve mood in most people. However, a very quick search for scientific papers on this link did not produce any convincing-looking hits. Maybe a longer search would.
So, here goes with a very rough, simplistic theory for exertion causing depression/low mood in ME.
This paper
http://jap.physiology.org/content/82/2/571
which I have referred to in other blogposts, reports that exertion increases intestinal permeability.
It states:
“Compromised barrier function may produce an inflammatory response and initiate a cytokine cascade...”
The authors also refer to bacterial endotoxins (aka lipopolysaccharides/LPS) entering the systemic circulation from the gut via increased gut wall permeability.
This paper
http://ini.sagepub.com/content/17/3/302
states that LPS trigger production of interferons.
Interferons can induce depression/low mood, as reported in numerous papers including this one:
http://www.jad-journal.com/article/S0165-0327(07)00332-1/abstract?cc=y
Why do people with ME get this adverse effect from exercise, yet others don't?
Perhaps it is due to our abnormal/inadequate HPA axis activity, which means that we can’t produce enough cortisol to dampen down the interferon activity (the link before last discusses cortisol and interferon signalling).
And/or maybe it’s because we switch to anaerobic ATP production too quickly, leading to excessive lactate levels/acidosis?
And/or maybe we don’t produce enough endorphins to combat adverse effects?
I’m keeping this post short as I have to get on with other stuff and am quite tired, but would welcome any comments.
